The disagreement between Street View’s 100:0 ratio of light to dark and my window’s less optimistic 50:50 ratio has been particularly jarring lately. What a tax on our brittle circadian rhythms!

I have created a bookmarklet to solve the simpler (street view) half of this disparity. Now, you can push a button to instantly cast any Street View scene into a weak approximation of darkness. The degree of night is based on what time it actually is in the corner of the world you’re viewing, combined with information on when the sun will rise or set.

An open Street View window, left unattended, will now cycle from day, to night, and back again, indefinitely. No longer will you leave the house under the false promise of daylight at your destination.

The algorithm is operating on the four sample scenes above. If you’d like to give it a try, drag and drop the link below into your bookmarks bar (for quick access) or right click and add it to your bookmarks (for less obtrusive access).

Next, navigate to Google Maps, and get into a Street View as you would otherwise. Once the view has loaded, give the new Street View Automatic link in your bookmarks bar a click to show the scene in its true (and current) light. Of course, if it’s actually daytime, you won’t see much change at all. The code also won’t work on embedded maps or portable devices.

My thanks to Jonathan Stott of Earthtools for making his excellent lat / lon to local time and sunrise / sunset API services available free of charge to the public.